Remain Connected--Even when you're frustrated by your situation, you can still hold hands as you talk, take breaks to give each other massages, share a joke, and keep your connection alive in simple ways. You can help one another through this!
Be Aware--If you always seem to fight about money, and especially if you don't entirely know why, it may be a good idea to examine your history and your partner's history and take a look at your 'money issues'. Just being aware of whether you carry negative patterns from childhood, unrealistic expectations, or 'hot buttons' that keep getting pressed, can help you to deal with your triggers.
Take a Break If You Need To--If things get too stressful, take a break and do something you both enjoy together, or take some time alone, and then come back after you both have a set of 'fresh eyes' and an extra dose of patience.
Remain Calm--I've said it before, and it's important enough to mention again. Staying calm when you're dealing with finances can make the difference between a fruitful planning session and a damaging altercation. See the suggestions above, or the resources below.